Stamper including a micro pattern

ABSTRACT

The present invention relates to stampers having micro patterns, and more specifically, the present invention relates to a stamper which enables to emit a color or form a character or a predetermined shape on a surface of an injection molded product owing to a pattern in a case the pattern is formed on the injection molded product by the stamper. 
     The stamper includes a stamper body, a plurality of micro patterns formed on a surface of the stamper body to be brought into contact with a surface of a product for the surface of the product to have a color or a shape, and spaces between the micro patterns.

TECHNICAL FIELD

The present invention relates to stampers having micro patterns, andmore specifically, the present invention relates to a stamper whichenables to emit a color or form a character or a predetermined shape ona surface of an injection molded product owing to a pattern in a casethe pattern is formed on the injection molded product by the stamper.

BACKGROUND ART

In a course of development of home appliances, though it has been atrend that the home appliances are developed focused on functions of theproducts or convenience of the users, moving further from the trend,currently a trend takes place, in which a user's sense of beauty istaken into account keeping a consumer's sense in mind.

As a result of this, though related art home appliances have exteriorsof achromatic colors, such as a white color, without patterns, recentlythe home appliances are made, not only to provide convenience of life tothe users, but also to become a portion of an interior design by makingcolorful decoration of the exterior of the home appliances and theexterior to become more splendid by using ornaments.

Especially, in a case the home appliance which forms a large empty frontspace, such as a refrigerator and an air conditioner, by placing adecorative panel on the front, the sense of beauty can be enhanced.

DISCLOSURE OF INVENTION Technical Problem

In the meantime, in decoration of the home appliance thus, a step isrequired, in which a color panel is placed on the home appliancedirectly and placing an ornament therein, and if characters are requiredat such a portion, a step for carving the characters therein isrequired.

Since such an addition of the steps costs time and expense, a technologythat can minimize such a cost has been required.

Technical Solution

To solve the problems, an object of the present invention is to providea stamper which can make easy generation of a color or easy formation ofcharacter or shape on a surface of a product.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, astamper includes a stamper body, a plurality of micro patterns formed ona surface of the stamper body to be brought into contact with a surfaceof a product for the surface of the product to have a color or a shape,and spaces between the micro patterns.

The micro patterns include widths of the micro patterns or pitchesbetween the micro patterns of 0.2 μm˜20 μm which enable to emit a colorfrom the surface of the product.

The micro patterns include widths of the micro patterns or pitchesbetween the micro patterns of 20 μm˜1000 μm which enable to form a shapeon the surface of the injection molded product.

The micro patterns include a linear shape.

The micro patterns include a shape surrounding a center point at thestamper so that the shape varies a color or a shape depending on adirection of a light incident on the micro patterns.

The micro patterns have circular shapes.

The micro patterns have hexagonal shapes.

The micro patterns have square shapes.

The stamper includes micro patterns having widths and pitches variedbetween parts thereof for varying colors emitting therefrom withpositions of a light incident on the micro patterns.

Advantageous Effects

The present invention has following advantageous effects.

If a color or a shape is required on a product, by transcribing themicro patterns on the stamper to the product, the color or the shape canbe formed easily without forming the required shape or painting thecolor on the product.

By making a color varied with an angle of view, a sense of beauty of theproduct can be enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 illustrate sections showing the steps of a method forfabricating a stamper in accordance with a preferred embodiment of thepresent invention;

FIG. 3 illustrates stampers each having a micro-pattern with the samepitches;

FIG. 4 illustrates stampers each having a micro-pattern with pitchesdifferent from one another;

FIGS. 5 to 8 illustrate the steps of a method for transcribing a micropattern by using a stamper having the micro pattern and an injectionmolding; and

FIGS. 9A˜9C illustrate photographs of products each having a micropattern transcribed thereto.

BEST MODE

Reference will now be made in detail to the specific embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

A method for fabricating a stamper in accordance with a preferredembodiment of the present invention will be described with reference toFIG. 1.

Referring to FIG. 1A, a sensitizing solution 20 is coated on a flatsubstrate 10 for forming a desired pattern. Then, as shown in FIG. 1B, amask 30 having a required pattern formed thereon is placed on the flatsubstrate 10, and an exposure is made to an upper side of the mask, toform a pattern 40 opposite to the pattern printed on the mask 30 on theflat substrate 10 at an upper side thereof.

It is preferable that the pattern 40 has a nano sized or a micro sizedpattern.

Referring to FIG. 2A, for making electroforming required for fabricationof the stamper, a metal seed layer 50 of a fixed thickness is coated onthe substrate 10 and the pattern 40, as shown in FIG. 2B, a structure 60of nickel Ni or copper Cu is formed by electroforming on the micropattern having the metal seed layer 50 coated thereon to cover the micropattern and the metal seed layer 50, and, as shown in FIG. 2C, if thestructure 60 is taken off the substrate, the stamper 60 having thedesired pattern can be fabricated.

In this instance, the stamper 60 includes a stamper body 60 which formsa body of the stamper 60, a micro pattern 62 on a surface of the stamperbody 60 for transcribing the pattern 40, and a space 63 between themicro patterns.

However, the stamper may have a variety of the micro patterns to varypatterns on a surface of the product which is formed as the stamper isbrought into contact thereto for producing variation of colors dependingon an angle of view on the product.

The micro pattern can be a linear pattern as shown in FIG. 3A, orhexagonal, or circular, or square patterns as shown in FIG. 3B, 3C, or3D, respectively.

The variety of micro patterns are arranged for mounting a product havingthe micro patterns transcribed thereto to a portion where decoration isrequired for producing a hologram effect in which a color vary with anangle of view when the user looks at the portion from an outside of theproduct.

A light has characteristics of a particle as well as a wave, showing aninterference phenomenon which is a characteristic of the wave. Theinterference is a phenomenon in which amplitude of a wave is augmented(Constructive interference) when phases of the wave are the same, andthe amplitude of the wave is diminished (Destructive interference) whenphases of the wave are opposite. If a white color meets with a medium tocause interference, a particular wave band causes constructiveinterference and other wave band causes destructive interference, todisplay colors.

If the light transmitting through the air meets with other medium, i.e.,a structure of the micro pattern, a portion thereof is reflected and theother portion thereof passes the micro pattern. In this instance, thelight passed through the micro pattern meets with the next micropattern, resulting in a portion thereof to be reflected and the otherportion thereof to pass the micro pattern. Such steps are repeated for anumber of times.

In this instance, in each of the steps, if the reflected light has aphase the same with a phase of an incident light, the constructiveinterference takes place, and if the reflected light has a phaseopposite to a phase of the incident light, the destructive interferencetakes place.

In the meantime, sometimes the color changes or disappears depending onthe structure of the micro pattern. If an interval of the micro patternson the stamper is adjusted, to make the interval to be formed on theproduct greater or smaller, the path of the light is changed, to causethe constructive interference, i.e., a wavelength of the reflected lightis also changed. Depending on an angle of the light incident on themicro pattern, a color of the reflected light also changes.

By taking the micro pattern, the characteristic of the light incident onthe micro pattern, and a direction of user's eyes, i.e., an indentdirection of the light, into account, and by adjusting pitches of themicro patterns and widths of the micro patterns, it is possible that acolor is sensed externally, and the color varies with the direction ofeyes.

In this instance, it is preferable that the width L and the pitch Sbetween the micro patterns at which the color can be displayed are setto be 0.2 μm˜20 μm taking a wavelength of the light incident theretofrom an outside, particularly, the wavelength of the visible light intoaccount. In this instance, the width and the pitch of the micro patternmay vary partly throughout the stamper, for making the color of thelight emitted from different parts to vary.

In the meantime, besides making the color to emit from the surface ofthe product having the micro pattern transcribed thereto as describedbefore, by making the width and the pitch of the micro pattern greaterthan the width and the pitch of the micro pattern at which the micropattern emits the color, it is possible to form a shape, such as acharacter, on the product.

In this instance, it is preferable that the micro pattern is formed suchthat the micro pattern can reflect entire wavelengths of the visiblelight, to reflect the incident light to an outside in a state the entirewavelengths of incident light are superimposed so that a portion wherethe micro pattern is formed appears to have colors of a white group.

For this, it is preferable that the width L and the pitch S of the micropattern is set to be 20˜2000 μm.

In the meantime, FIG. 4 illustrates stampers each having a micro-patternwith pitches S1 and S2 different from one another, to make the incidentlight onto the stamper different depending on incident positions forvarying colors emitted from respective parts.

A method for fabricating a product by using a stamper having a micropattern will be described. Though there are hot stamping and injectionmolding in the method, the following description will be based on theinjection molding which enables fast production of the product.

Referring to FIG. 5, the injection molding machine 1 having the stamperwith the micro pattern of the present invention includes a first moldunit 10, a second mold unit 20, and the first mold unit 10 has a cavity11 for introducing molten resin thereto.

It is preferable that the first mold unit 10 has a heating unit, such asa first heater 13, mounted therein for preventing the resin fromsolidifying at the time of injection molding, and a cold water flowpassage 12 built therein for flow of cooling water.

The second mold unit 20 has a second heater 22 mounted therein forheating the second mold 20, and a cooling mold 30 in rear of the secondheater 22 for cooling the second mold 20.

The cooling mold 30 is movably arranged at a receiver 25 mounted in thesecond mold 20 separately, and the receiver 25 has a guide member 40 forguiding movement of the cooling mold 30.

The cooling mold 30 and the second mold 20 have an electric magnet 35and a permanent magnet 59 arranged thereto respectively. If the electricmagnet 35 and the permanent magnet 59 are arranged thus and a current isapplied to the electric magnet 35, an attractive force or repulsiveforce is generated between the electric magnet 35 and the permanentmagnet 59. If the attractive force is generated, the cooling mold 30 andthe second mold 20 are brought into contact to cool down the second mold20.

The cooling mold 30 has a cooling water flow passage 33 formed thereinfor flow of cooling water. If cooling of the second mold unit 20 isrequired, the cooling water is introduced to the cooling water flowpassage 33 to cool down the second mold unit 20 and the stamper 9 to bedescribed later quickly, causing solidification of the resin filled inthe first and second mold units 10 and 20, to form a molded product.

At a side of the first mold unit 10, there is a first mold supportingblock 58, and there is a second mold supporting block 60 spaced adistance away from the first mold supporting block 58 for supporting thesecond mold unit 20.

In rear of the second mold 30, there is a mold moving unit 38 projectedfrom the second mold supporting block 60 for making the second mold 20to move to or move away from the first mold unit 10.

On one side of the first mold supporting block 58, there is a resinsupply unit 80 for moving molten resin to the first mold unit 10, andover the resin supply unit 80, there is a hopper 70 for receiving themolten resin.

In this instance, it is preferable that there are a resin flow passage82 provided to pass through the resin supply unit 80, the first moldsupporting block 60, and the first mold unit 10 for guiding the moltenresin from an outlet of the hopper 70, with a screw 83 arranged thereinfor making quick transfer of the molten resin to the first mold unit 10.

Under the first and second mold supporting blocks 58 and 60 and theresin supply unit 80, there is a base block 84 for supporting them.

In the meantime, at one side of the second mold unit 20, there is thestamper 9 having the micro pattern 9 b provided thereto, and at asurface of one side of the second mold unit 20, there is a stamperattachment portion 20 a provided thereto for attaching the stamperthereto.

Though the drawing shows an enlarged view of the micro pattern 9 b onthe stamper for showing the micro pattern 9 b clearly, the micro pattern9 b is invisible with naked eyes.

It is preferable that the stamper attachment portion 20 a has a fixture,such as a holder (not shown) or a jig (not shown) for fastening thestamper not to make position change when the stamper 9 and the moltenresin are brought into contact with each other in the injection molding.

The stamper 9, formed of a metal like nickel, has in general a surfacetemperature significantly lower than the molten resin used in theinjection molding.

Therefore, since there is a problem in that the resin solidifies beforethe micro pattern 9 b is patterned to resin perfectly if the stamper 9having a relatively low temperature and the molten resin having a hightemperature are brought into contact, it is required to maintain thestamper 9 to be at a temperature higher than a glass transitiontemperature of the polymer of the resin.

The glass transition temperature is a temperature at which a polymerbecomes to have activity and begins to move. The polymer resin is in asolid state at a temperature below the glass transition temperature, andif the polymer resin is at a temperature higher than the glasstransition temperature, the polymer resin turns to have elasticity, likerubber, and if the temperature becomes higher, the polymer resin turnsto liquid at the end.

Accordingly, it is required that a liquid state of the resin ismaintained for a predetermined time period for forming a pattern thesame with the micro pattern on the stamper on an injection moldedproduct exactly as the liquid state resin is brought into contact withthe stamper 9. Therefore, it is required that a surface temperature ofthe stamper is at the glass transition temperature for the time period.

In the meantime, a temperature control unit 85 is provided to the baseblock 84 of the injection molding machine.

Since a main purpose of the cooling mold 30 and the second heater 22mounted to the second mold unit 20 is fast heating and fast cooling ofthe stamper 9, mostly the temperature control unit 85 serves to makefast temperature control of the surface of the stamper 9.

Injection molding with the stamper 9 having the micro pattern 9 b formedthereon in accordance with a first preferred embodiment of the presentinvention will be described.

Referring to FIG. 6, the stamper 9 having the micro pattern 9 b isfastened to the stamper attachment portion 20 a of the second mold unit20. Then, upon applying an instruction that the surface temperature ofthe stamper 9 and the first and second mold units 10 and 20 are to behigher than a predetermined temperature to an operational button, acurrent flows to the first and second heaters 13 and 22 to heat thefirst and second mold units 10 and 20 by heat resistance, along with thestamper 9 to be higher than the predetermined temperature.

In general, a time period in which the stamper 9 reaches to thepredetermined temperature, for an example, the glass transitiontemperature, is around one minute from right after the heaters are putinto operation.

In this instance, since current flows to the electric magnet 35 togenerate repulsive force between the permanent magnet 28 and theelectric magnet, the second mold 20 and the cooling mold 30 maintain aspaced state.

Referring to FIG. 6, while the second mold unit 20 and the cooling mold30 maintain the spaced state thus, and the first and second mold units10 and 20 and the stamper 9 maintain the heated state, if the secondmold unit 20 moves to the first mold unit 10 until the second mold unit20 and the first mold unit 10 are brought into close contact, anenclosed cavity 11 of a shape of the product is formed between the firstmold unit 10 and the stamper 9.

Referring to FIG. 7, in a state the second mold unit 20 and the firstmold unit 10 are in close contact to form the enclosed cavity 11, themolten resin R is introduced to the cavity 11 by means of the screw 83moving in the resin flow passage 82 to fill the cavity 11 and betweenthe micro patterns 9 b on the stamper 9, to transcribe the micro pattern9 b as it is.

Then, if the first and second heaters 13 and 22 are turned off, and arepulsive force is generated between the electric magnet 35 and thepermanent magnet 59, the cooling mold 30 is brought into contact withthe second mold 20, and at the same time with this, if the cooling wateris introduced to the cooling water flow passage 33 in the cooling mold30 and the cooling water flow passage 12 in the first mold 10, the firstand second mold units 10 and 20 and the stamper 9 are cooled, tosolidify the resin filled in the cavity 11.

Then, referring to FIG. 8, the second mold unit 20 is moved away fromthe first mold unit 10, to obtain the injection molded product F havingthe micro pattern 9 b on the stamper 9 transcribed thereto from thecavity 11.

As described before, by varying the pitch and width of the micro patternon the stamper 9, a color from a surface of the injection molded productF can vary.

In the meantime, besides the injection molding, the product can beobtained by so called hot stamping in which a heated stamper is broughtinto contact with a resin product to transcribe the micro pattern on thestamper to the surface of the resin product.

FIGS. 9A˜9C illustrate photographs of products each having a micropattern transcribed thereto so as to emit a color or form a shape.

FIG. 9A illustrates an ornamental panel made to emit a color by using astamper having a micro pattern, wherein petal shaped outline portionsare made to emit the color by using the stamper.

As described, a portion indicated with A has micro patterns with 0.2˜20μm pitches which emits a color.

FIG. 9B illustrates an ornamental panel having a portion emitting acolor and a portion displaying characters, wherein an A portion emittinga color has micro patterns with 0.2˜20 μm pitches, and B portiondisplaying characters has micro patterns with 20˜2000 μm pitches.

FIG. 9C illustrates a panel having characters and figures displayed in awhite color, wherein portions of the characters and the figures areformed by a stamper having micro patterns with 20˜2000 μm pitches.

1. A stamper comprising: a stamper body; a plurality of micro patternsformed on a surface of the stamper body to be brought into contact witha surface of a product for the surface of the product to have a color ora shape; and spaces between the micro patterns.
 2. The stamper asclaimed in claim 1, wherein the micro patterns include widths of themicro patterns or pitches between the micro patterns of 0.2 μm˜20 μmwhich enable to emit a color from the surface of the product.
 3. Thestamper as claimed in claim 1, wherein the micro patterns include widthsof the micro patterns or pitches between the micro patterns of 20μm˜1000 μm which enable to form a shape on the surface of the injectionmolded product.
 4. The stamper as claimed in claim 1, wherein the micropatterns include a linear shape.
 5. The stamper as claimed in claim 1,wherein the micro patterns include a shape surrounding a center point atthe stamper so that the shape varies a color or a shape depending on adirection of a light incident on the micro patterns.
 6. The stamper asclaimed in claim 5, wherein the micro patterns have circular shapes. 7.The stamper as claimed in claim 5, wherein the micro patterns havehexagonal shapes.
 8. The stamper as claimed in claim 5, wherein themicro patterns have square shapes.
 9. The stamper as claimed in claim 1,wherein the stamper includes micro patterns having widths and pitchesvaried between parts thereof for varying colors emitting therefrom withpositions of a light incident on the micro patterns.